Not Applicable
Not Applicable
1. Field of the Invention
This inventions relates to radio frequency identification (RFID) tags, and more particularly active RFID tags that include a battery and an antenna as integral parts thereof.
2. Description of the Related Art
Objects associated with inventory, product manufacturing, merchandising, and related operations create challenges for accurately monitoring of the location and flow of the objects. There is a continuing need to determine the location of these objects, and to track relevant information about the objects. A tag device suitably configured to be associated with any of a variety of objects, including goods, items, persons, or animals, or substantially any moving or stationary and animate or inanimate object, which facilitates location and data tracking, can be used. One such tag tracking system is an electronic identification system, such as RFID. RFID tags are attached, connected, or in some way associated with an object for the purpose of tracking the object, and storing and retrieving information about the object.
Information related to the object to which an RFID tag is attached can be written to and stored in memory in the RFID tag. The RFID tag will be detected in a suitable electromagnetic field, and the information stored in the tag can be read, and changed if desired. Typically, the RFID tag devices are entirely passive (have no onboard power supply), which results in a small and portable package. However, passive tags are only capable of operation over a relatively short range, limited by the size of the field used to supply power and to communicate with the tags.
An active RFID tag includes a power supply connected to the tag to increase the detectable range. However, with the addition of a battery the RFID tag becomes physically larger, and more expensive. RFID tags must be thin and flexible to maintain usefulness in many applications. Larger and more rigid tags will reduce the usefulness of the tag by restricting applications.
The invention provides an active radio frequency identification label, which includes a radio frequency identification chip disposed on a substrate. A battery disposed on the substrate is connected to the radio frequency identification chip. At least a portion of the battery forms an antenna for the radio frequency identification chip.
The antenna can be a dipole antenna adapted for operation at microwave frequencies. Alternately, the antenna may operate at other than microwave frequencies, such as 8 MHz or 13.56 MHz.
The battery can be a thin-film battery. The thin-film battery may be a lithium-ion battery.
The battery typically includes two electrodes separated by an electrolyte, and the antenna is formed from at least one of the electrodes.
The antenna and the battery can be substantially co-located on the substrate so that the battery does not take up any additional space.
A method for powering the a radio frequency identification label, includes providing a radio frequency identification label including a radio identification chip disposed on a substrate and including a thin-film battery, a portion of the battery forming an antenna for the radio frequency identification chip. And placing the radio frequency identification label in a radio frequency identification electromagnetic field formed by a radio frequency identification reader. Where the radio frequency identification electromagnetic field powers the radio frequency identification chip whenever the power available from the field is greater than the power available from the battery. And where the battery powers the radio frequency identification chip whenever the power available from the field is less than the power available from the battery.
The method for powering further provides charging the battery whenever the power available from the radio frequency identification electromagnetic field is greater than the power available from the battery.
Objectives, advantages, and applications of the present invention will be made apparent by the following detailed description of embodiments of the invention.